For public or business infrastructure systems bearing social foundations, high availability has been desired. For this reason, in the data storage market, so-called Disaster Recovery System has been demanded that will not lose data even if a storage apparatus holding a huge amount of data were destroyed by disasters, for example.
As one of the techniques to meet to such a market request, a computer system has been provided that backups data using a remote copying technique. This computer system stores identical data into storage apparatuses placed at two sufficiently distant locations. When the data in either one of the storage apparatuses is updated, the update is synchronously or asynchronously reflected to the other storage apparatus by means of remote copying. Consequently, the identity of the data in the two storage apparatuses is secured.
To further improve the security of the data, PTL 1 discloses a storage system that provides storage apparatuses at three sufficiently distant locations from one other. In this computer system, the identity of the data between the first storage apparatus to be used in normal service and the second, remote storage apparatus is secured by synchronous remote copying. On the other hand, the identity of the data between the first storage apparatus and the third remote storage apparatus is secured by asynchronous remote copying.
As a technique to effectively utilize computer resources such as CPUs, memory devices, and storage apparatuses, system virtualization technique is disclosed in NPL 1 and NPL 2. According to this technique, a plurality of virtual machines (also referred to as guests) are provided on a physical computer and the physical computer can function as if a plurality of computers were working. This technique is utilized for effective use of surplus computer resources or server consolidation that integrates several hundreds of guests into a single high-performance computer.
A virtual machine is a server environment attained by software; a single OS runs on the virtual machine to allow applications to run. Accordingly, for data protection, a range in which data integrity is to be preserved is expected to include volumes used by a virtual machine. In other words, it is desired that a system virtualization program distinguish a group of volumes allocated to a virtual machine from a group of volumes allocated to other virtual machines and perform remote copying of the group of volumes.